I have completed my Haynes roadster chassis and fitted all the plates, just about ready to spray it. I have now laid it on the garage floor on 25mm
RHS tubes to measure the engine mounts and now I find that it is not completely flat!!!!!
The base rail at the front one one side is 4mm higher so it doesn't lie completely flat. I checked and checked the table I built it on and it
was flat and even, but either the table warped during the build or the floor it was on was not completely even. AARRGGHH!
The question is...... is this a manageable error or not. All the wishbones are made and have been dry fitted without problems and all their
measurements in relation to frame are exact.
Grateful for advice. Thanks
personally OI thing you will get away with 4mm you could always weld the supension mounts slightly off to recover the difference
Maybe not for racing competitivly but for road use I'd not have an issue with that, tbh my Landrover is at least 10mm out across the chassis, some times the doors open by themselves spooky. Other cars you jack up a wheel and the doors don't shut, most flex a lot on the road. I'd say you 4mm is trivial, you'd most likely never feel the difference.
Get the suspension set up properly (4 wheel full-on alignment jobbie if you've got adjustable suspension) when you're finished, and
you'll be fine. This will make far more difference than the 4mm in the chassis.
4mm across the car is not catastrophic. Production cars don't tend to get much better than 2mm out to give you an idea.
4mm warp on a home built chassis is good, and as long as the suspension brackets are in the right place it will be OK.
Are you sure it's real, measurement is probably not that easy, you need some flat reference?
4mm does not sound so bad, never checked the MK chassis, would not be surprised if it was similar..
Is the garage floor completely flat?
Do some diagonal check dimensions, will give a better idea of how 'square' it is.
After many years of driving and hooning I would be supprised if my chassis was less than 4mm out. Thats what a geo set up can dial out.
Mine is 6 mm off.
I Split the difference and welded the brackets level.
I think 3 mm each side will be very difficult to see for the undiscerning eye, let alone at high speed spirited driving.
You mention that you put it on the garage floor on top of 25mm tubes? I have noticed that even a tube of that thickness will curve slightly over the
length of a car (especially with a bit of weight on top of it), and if your garage floor isn't flat the tube will end up lifting at one end. I
tried doing the same, and I was getting different measurements depending on where they were laid in the garage.
As a general question, what is the best way of checking a table is flat?
Flat and level are different things. You can check for level using a simple water gauge, on the four outside corners of the table.
Flat is a little bit more difficult, possibly using a laser level from one corner and measuring the beam height along the table.
Of course if you can find a spirit level as long as the table, you can solve both problems
Or as the FIA would put it:-
You need to check the vertical variation of the horizontal diagonals.
Paul G
quote:
Originally posted by 907
Or as the FIA would put it:-
You need to check the vertical variation of the horizontal diagonals.
Paul G
3mm is standard acceptable tollerance on production cars, why do you think cars have adjustable suspension?